As one of major components of a thin film transistor liquid crystal display (TFT-LCD), a liquid crystal panel usually includes an array substrate and a color filter substrate arranged opposite to each other, a sealant adhered between the array substrate and the color filter substrate, and liquid crystals filled within a cell structure formed by the array substrate, the color filter substrate and the sealant. During the manufacturing of the liquid crystal panel, the liquid crystals are instilled onto the array substrate by one drop filling (ODF), the sealant is applied onto a periphery of the color filter substrate, and then the array substrate and the color filter substrate are arranged opposite to each other to form a liquid crystal cell.
In the process for manufacturing the liquid crystal panel, the amount of the liquid crystals in the liquid crystal cell needs to be determined in accordance with design requirements as well as tiny adjustments in the actual procedure. The liquid crystal panel is extremely sensitive to the amount of the liquid crystals, and too many or too few liquid crystals will directly lead to the occurrence of blackspots, light leakage or white light for a display image of a display device, and thereby the display quality will be adversely affected. Hence, it is required to accurately measure the amount of the liquid crystals.